The first NDS Homebrew game for the developer, based on an old board game called Black Box.
The basic premise is that you shoot rays into the game board and based on their behavior, you are able to locate hidden crystals. A ray can HIT the crystal, be REFLECTED back the way it came in or be DEFLECTED out another way. The rules are a little tricky to catch on to at first but after you get the hang of it, the game is very addictive.
Official Homepage: http://foutsnet.com/homebrew/